A virtual computing environment may include a very large number of host computers. A host computer provides a virtualization layer for hosting one or more virtual machines (VMs). A virtualization management module carries out administrative tasks for the virtual computing environment, including managing hosts, managing VMs running within each host, provisioning VMs, migrating VMs from one host to another host, and load balancing between hosts. In order to verify that a virtualization management module will work properly at a large scale, simulations of the virtualization management module need to be performed. Existing simulators are handcrafted simulators that require a user to explicitly lay out the topology of the virtual computing environment: the number of hosts, the connections to datastores, etc. Building a topology manually becomes very difficult when the virtual computing environment contains hundreds or even thousands of hosts.